Apparatus for stringing tennis rackets



April 18, 1939. Epl-l, SERRANO APPARATUS FOR STRINGING T ENNIS RACKErISFiled June lO, 1936 3 Sheets-Sheet l Il l lllllll 3mm. Se frana April1s, 1939.

E. H. SERRANO APPARATUS FOR STRINGING TENNIS RACKETS 3 Sheets-Sheet 2Filed June 1o, 195e EHSfF/TZO pf 18, 93@ 'E H SERRANO S-,g'o

APPARATUS FOR STRINGNG TENNIS RACKETS Filed June lO, 1936 3 Sheets-Sheet3 A@wem/bof@ Serra n GMM/MAMA Patented Apr. 18, 1939 UNITED STATESPATENT OFFICE APPARATUS FOR STRINGING TENNIS RACKETS 4 Claims.

This invention relates to certain new and useful improvements inapparatus for stringing tennis rackets.

An object of the invention is to provide apparatus for the Stringing oftennis rackets and including a tensioned device that is manuallyoperated for the stretching of a string and constructed in a mannerwhereby a pulling strain on the string beyond a predetermined point isremoved so that the strings may be stretched to the desired degreeregardless of continued movement of the tensioning device.

A further object of the invention is to provide apparatus for theStringing of tennis rackets that includes a support for the racket witha string tensioning device movably supported relative to the racket forpositioning relative to the string openings in the racket frame withmeans for holding the tensioning device against movement whereby thehands of the operator are free for other work in connection with theStringing of the racket.

With the above and other objects in View that will become apparent asthe nature of the invention is better understood, the same consists inthe novel form, combination and arrangement of parts hereinafter morefully described, shown in the accompanying drawings and claimed.

In the drawings:

Figure l is a top plan view of apparatus for Stringing tennis racketsconstructed in accordance with the present invention and illustrating atensioning device for the string engaged with the frame of the tennisracket and illustrated by dotted lines in a shifted position;

Figure 2 is a side elevational view, partly in section, showing theadjustable mounting for the brackets that support the string tensioningdevice;

Figure 3 is a fragmentary sectional view of the string tensioningdevice, the string frame of the tennis racket and an arm of a stringclamp;

Figure 4 is a detail sectional view taken on line 4--4 of Figure 3,showing a tennis string encircling the drum or casing of the tensioningdevice and a part of the string frame of the racket with the stringextending through an opening in the frame;

Figure 5 is a top plan View of the string tensioning device showing ascale or gage for determining pulling strains on the strings;

Figure 6 is a detail sectional View taken on line 6 6 of Figure 2,showing the string clamp and the removable handle for positioning oneither side of the clamp;

Figure 7 is a plan view of one of the friction disks in the stringtensioning device;

Figure 8 is a detail sectional View taken on line 8 8 of Figure l,showing the clamping device for the handle of the tennis racket;

Figure 9 is a detail sectional View taken on line 9--9 of Figure 2,showing mounting bars for the string clamp;

Figure 10 is a detail sectional View taken on line lil-l0 of Figure 1,showing the clamp for the outer end of the string frame of the tennisracket.

Referring more in detail to the accompanying drawings, and particularlyto Figures 1 and 2, a tennis racket is illustrated and of the usual formthat embodies an oval-shaped string frame that is carried by a handle 2I, the tennis racket being mounted in a support and rigidly held thereinduring the Stringing operation. The string frame 2E! is provided withthe string openings 22 as shown in Figure 2 for the passage of thestrings Z3 shown in Figure l. A support for the tennis racket comprisesa base block 24 adapted to be anchored to a table, bench 25 or the likeand from which a standard 26 rises with clamping devices at the upperend of the standard 26 for the support of the handle 2l of the tennisracket as shown in Figures 1, 2 and 8. rI'he handle clamp comprises aU-shaped frame having a bottom wall 2l and upstanding side walls 28, aclamping plate 29 being associated with the inner side of each side wall23 for direct engagement with the handle 2i of the tennis racket and tobe moved into clamping engagement therewith by means of the clampingscrews 30 threaded through the side walls 28, the clamping screws beingpreferably arranged to provide one clamping screw for a side wallintermediate the ends thereof and two spaced clamping screws for theother side wall of the clamp as shown in Figure 1, the screws beingadjustable to obtain proper positioning of the tennis racket in theStringing apparatus. A horizontal bar 3l projects from the lower end ofthe standard 2B beneath the tennis racket and terminates outwardly ofthe outer end of the string frame 2li and upon which end a support forthe string frame of the racket is mounted. As shown more clearly inFigures 2, 9 and 10, an arm 32 has a bearing 33 at its lower end formounting on the bar 3l, the arm being of angle formation to present theupper end 34 thereof for the support of the outer end of the stringframe 20. The string frame of the racket is mounted on the upper end 34of the arm 32 and a clamp plate 35 is engaged with the upper side of thestring frame 20 and retained in clamping engagement therewith by meansof the clamping screw 36 passing through an opening in the clamp plate35 and having threaded engagement as at 31 with the upper end 34 oi thearm. It will therefore be seen that a rigid mounting is provided for thetennis racket.

The string tensioning device and support therefor is shown more clearlyin Figures 1 to 5, the support including a bracket 38 projecting horivsozontally from the support 25 beneath the bar 3|, the bracket 38terminating inwardly of the outer end of the bar 3| and to the outer endof which bracket, an arm 39 is pivotally mounted and retained inadjusted positions by means of the clamping screw 40. An upstandingbracket arm 4| is carried by the arm 39 and is slidably mounted thereonby means of the guide 42, a lug 43 at the outer end of the arm 3Spreventing displacement of the guide 42 and the string tensioning deviceis mounted upon the upper end of the bracket arm 4|. As shown in Figure3, the string tensioning device comprises a metallic cylinder 44surrounded by a rubber casing 45 and about which the string 23 isadapted to be wound with the rubber casing preventing injury to thestring as well as the outer edge of the string frame 26 of the racket.The upper end of the cylinder 44 is closed by a disk 46 and the lowerend of the cylinder is closed by a disk 41 upon which the cylinder 44and rubber casing 45 rests with a central upstanding portion 48 on thebottom disk 41 rising into the cylinder 44 as illustrated. A handle 46projects peripherally from the bottom disk 41 for manipulation thereof.A spindle 56 located axially within the cylinder 45 has the upper endthereof threaded for the reception of a cap nut 5| that passes through acentral opening in the top disk 46 for engagement with the upperthreaded end of the spindle 58, the cap nut having a flange at its upperend engaged with the top disk 46 to retain the same in position in thecylinder 44. As shown in Figure 5, the top disk 46 is calibrated as at52 in pounds tension and the cap nut 5| carries an indicator pointer 53cooperating with the calibrations 52. The lower end of the spindle 56extends through the disk 48 and also through a central opening in a topWall 54 at the upper end of the bracket arm 4|, the spindle being freelyrotatable through the bottom disk 48 and wall 54. A sleeve 55 isthreaded onto the lower threaded end 56 of the spindle 56, the sleeveextending through an opening in the wall 54 and abuttingly engaging thelower side of the bottom disk 48, the sleeve 55 being retained inadjusted position by means of the lock nut 51 threaded onto the lowerend of the spindle and engaged with the sleeve. For purposes presentlyto appear, a disk plate 58 is freely mounted on the sleeve 55 in flatengagement with the underside of the wall 54 and is retained in positionon the sleeve by mating inclinedv surfaces 59 as illustrated. A handle66 is pivotally mounted at one end as at 6| upon the disk plate 58adjacent one side edge thereof, the handle 66 carrying a cam portion 62adjacent its pivot point for engagement with the wall 54 for holding thespindle 56 against rotation. A series of metallic and bre disks 63 aremounted on the spindle 50 and rest upon the upper face of the extension48 of the bottom disk 41, selected ones of the disks 63 as shown inFigure '7 having diametrically opposite peripheral lug projections 64that work in side slots 65 in the cylinder 44 to retain certain ones ofthe metallic disks 63 against rotation while other disks 63 havingsquare central openings tting on a squared portion of the shaft 56 asshown in Figure 4 to rotate with the shaft to produce friction betweenthe disks during relative movements of the disks that is shown on theindicator devices 52 and 53. A series of coil springs 66 are interposedbetween the top disk 46 and the upper friction disk 63 within thecylinder 44, the springs being retained in position by pins 61 dependingfrom the top disk 46 and lugs 68 struck out and rising from the topfriction disk 63. When the cap nut 5| is rotated by the insertion of animplement in the opening 5|arr thereof, the indicator finger 53 iscaused to register with the desired calibration 52 indicating tension inpounds and during such movement, the top disk 46 of the cylinder 44 islowered into the cylinder for compression of the springs 66 forincreasing friction between the several disks 63. The tennis racketstring 23 is passed around the cushion covering 45 on the tensioningdevice as shown at 23a, the elastic covering 45 preventing slippage ofthe looped portion 23a of the string, the tensioning device beingpositioned with respect to the string frame 20 of the racket as shown inFigures 1 to 4. The handle 49 of the tensioning device rotates thecylinder 44 to place the string 23 under the desired tension and whensuch tension has been attained as determined by the initial settingpoint of the dial of the tensioning device, the string tension iovercomes friction between several friction disks 63, the bottom disk 41of the cylinder 44 and the wall 54 at the upper end of the bracket arm4|, the handle at this moment being permitted to move independently ofthe cylinder 44 so that only a predetermined degree of tension can beimparted to the string 23.

When the tennis racket string 23 has been placed under the desiredtension, a clamp is engaged with the string Within the frame 20 of thetennis racket for holding the string against movement relative to theracket frame 26 and permitting shifting movement of the tensioningdevice to a position for stretching a string through another opening 22of the racket frame. Before the clamp is engaged with the string, thetensioning device is restrained from movement after having placed thestring under the desired tension by means of the lever 68 that moves itscam 62 into engagement with the wall 54 at the upper end of the bracketarm 4 i, this action causing the plate 58 to lower the spindle 56 by itsengagement with the threaded sleeve 55 for causing a further compressionof the springs 66 and correspondingly increased pressure on the frictiondisks 63. The tensioning device is thereby held against rotary movementon the bracket arm 4| until the clamp is engaged with the string and atwhich time the tensioning device may be released. The string clamp andsupport therefor are shown more clearly in Figures 1 to 3, 6 and 9, thesupport including a pair of horizontal arms 69 projecting respectivelyfrom opposite sides of the bar 3| adjacent the lower end of the standard26 that rises from the base block 24 with a rod 16 having a bearingsleeve 1| at one end mounted on each arm 69. The support for the forwardends of the rods 16 includes a pair of interiitting blocks 12 slidablymounted upon the bar 3| and as shown in Figures 2 and 9, each block 12carries an outwardly directed arm 13 having a longitudinal groove 14 inone side thereof for receiving the reduced pin end 'l5 of the adjacentrod 16, the rods 16 supporting the clamps for Stringing the lateralstrings while the clamps are mounted on the arms 13 when Stringing thecross strings. The string clamp per se as shown in detail in Figure 6comprises a pair of clamp plates 16 having semi-circular barrel portions11 at their lower ends for engagement with the rods 10 as shown inFigure 6 or for engagement with the arm 13. The upper ends of the clampplates 16 are serrated as at 18 to provide spaced fingers 19 tofacilitate positioning of the upper ends of the clamp plates throughcrossed strings for clamping engagement with a string. The connectionbetween the two clamp plates 16 comprises a headed screw bolt 80 freelypassing through the clamp plates intermediate the ends thereof, a handle8i for operation of the clamp plates 16 being mounted upon the threadedends of the bolt 80 and retained thereon by the nut 82. The pivoted endof the handle 8| carries a cam block 83 for effecting movements of theclamp plates toward and away from each other. A coil spring 84 isinterposed between the clamp plates 'Iii to effect separation thereoffor releasing the engagement between the clamp plates and the string 23and also the supporting rod lo or arm 13, the screw bolt 80 andoperating handle 8| being reversible for mounting upon either side ofthe clamp plate as may be desired in connection with the Stringing of atennis racket. When the desired tension has been placed upon the string23 by the tensioning device and the latter restrained from movement bythe locking lever Eil and cam 62, the clamp plates are then engaged witha string, whereupon the tensioning device may be released and shifted byits pivotal and slidable mounting to a position to receive a string tobe wound thereon from the adjacent racket frame opening 22. Thesupporting rods 'I0 are used for the mounting of the clamps whenStringing the lateral strings and these rods 10 may be removed and theclamps mounted on the arms 'I3 when Stringing the cross strings of theracket frame.

From the above detailed description of the invention, it is believedthat the construction and operation thereof will at once be apparent andwhile there are herein shown and described the preferred embodiments ofthe invention it is nevertheless to be understood that minor changes maybe made therein without departing from the spirit and scope of theinvention as claimed.

I claim:

l. In the Stringing of tennis rackets, wherein a string tensioningdevice is adapted to have a string coiled therearound to exert a pullingforce on a string threaded through a tennis racket and to be uneffectiveduring continued movement after the string has received the desiredtension, and wherein a tensioned portion of the string is held undertension while the tensioning device is being engaged with anotherportion of the string and wherein means is provided for holding thetensioning device against movement, a tensioning device including ahandle having a disk at one end, a rubber covered cylinder supported onthe disk and about which the string is adapted to be coiled, a frictiondevice within the cylinder and associated with the disk, and means forVariably tensioning the friction devices whereby a predetermined tensionmay be applied to the string.

2. lIn the Stringing of tennis rackets, wherein a string tensioningdevice is adapted to have a string coiled therearound to exert a pullingforce on a string threaded through a tennis racket and to be uneifectiveduring continued movement after the string has received the desiredtension. and wherein a tensioned portion of the string is held undertension while the tensioning device is being engaged with anotherportion of the string and wherein means is provided for holding thetensioning device against movement, a tensioning device including ahandle having a disk at one end, a cylinder mounted on said disk, aspindle journaled through the disk, a calibrated disk at the outer endof the cylinder, an indicator finger on the outer end of the spindlecooperating with the calib-rated disk, and spring devices associatedwith the cylinder, spindle and disk for variably tensioning the handledisk whereby a predetermined tension may be applied to the string.

3. In the Stringing of tennis rackets, wherein a string tensioningdevice is adapted to have a string coiled therearound to exert a pullingforce on a string threaded through a tennis racket and to be uneffectiveduring continued movement aiter the string has received the desiredtension, and wherein a tensioned portion of the string is held undertension while the tensioning device is being engaged with anotherportion of the string and wherein means is provided for holding thetensioning device against movement, a tensioning device including ahandle having a disk at one end, a spindle journaled through the diskand threaded at its upper end, a rubber covered cylinder surrounding thespindle and supported on the disk, a calibrated disk at the outer end ofthe cylinder, and slidably mounted therein, a cap screw threaded on thespindle and engageable with the calibrated disk to move the same intothe cylinder, an indicator finger on the cap screw cooperating with thecalibrated disk, a series of frictionally engaged disks on the spindlewithin the cylinder, some of the disks being interlocked with thecylinder and other disks interlocked with the spindle, springsinterposed between the calibrated disk and the series of disks and saidcap screw adapted to be adjusted for variably tensioning the frictiondiskswhereby a predetermined tension may be applied to a string.

ll. In the Stringing of tennis rackets, wherein a string tensioningdevice is adapted to have a string coiled therearound to exert a pullingforce on a string threaded through a tennis racket and to be uneiectiveduring continued movement after the string has received the desiredtension, and wherein a tensioned portion of the string is held undertension while the tensioning device is being engaged with anotherportion of the string and wherein means is provided for holding thetensioning device against movement, a tensioning device including ahandle having a disk at one end, a spindle journaled through the diskand threaded at its upper end, a rubber covered cylinder surrounding thespindle and supported on the disk, a calibrated disk at the outer end cfthe cylinder, and slidably mounted therein, a cap screw threaded on thespindle and engageable with the calibrated disk to move the same intothe cylinder, an indicator finger on the cap screw cooperating with thecalibrated disk, a series of frictionally engaged disks on the spindlewithin the cylinder, some of the disks being interlocked with thecylinder and other disks interlocked with the spindle, springsinterposed between the calibrated disk and the series of disks and saidcap screw adapted to be adjusted for variably tensioning the frictiondisks wherebsr a predetermined tension may be applied to a string, asupport for the tensioning device and the means for holding thetensioning device `against movement including a cam device for movingthe calibrated disk and spindle to increase friction between the handledisk and support.

EDMUNDO H. SERRANO.

